In another thread in the beginners forum (where the mud slinging has reached a level where I don't want to contribute.) it is suggested that opposite and opposed loockers at a top rope anchor is somehow less safe than double lockers oriented.

Does anyone agree? I'd say that though OnO biners makes it more likely for one gate to be rubbed, pressed and opened against the rock it makes it far less likely for both biners to be compromised.

Not really a beginners question, but since the discussion originated in this forum I'll keep it here.

Oh, and I do know that O-n-O is a pain with some biner shapes. Actually with most anything but ovals. However that was not the original point.

In 37 years I don't think I've ever TR'd with two lockers, just two opposed non-locking biners or draws. I suppose if you're paranoid or engaged in group commerce, but seems like overkill to me no matter how you orient them (which in itself also seems like a silly subject).

In 37 years I don't think I've ever TR'd with two lockers, just two opposed non-locking biners or draws. I suppose if you're paranoid or engaged in group commerce, but seems like overkill to me no matter how you orient them (which in itself also seems like a silly subject).

Agreed, and I'd top rope on opposed non-lockers any day of the week myself. Wouldn't (normally) top rope on a single locker though. The risk might be minimal, but it seems sloppy. (And there is absolutely no excuse for sloppyness in a top rope anchor)

However what you or I climb on was not the question. In the thread that I linked to it was suggested that using two lockers with gates to the same side is safer than the same lockers o-n-o. Since this is the beginners forum I'd like to have that statement verified or debunked.

(Yes I do agree that opposed lockers can be overkill. I also agree that D-shaped biners can pinch the rope thus nullifying the effect of a greater bend radius which is one good reason to add a second biner.)

I also agree that D-shaped biners can pinch the rope thus nullifying the effect of a greater bend radius which is one good reason to add a second biner.

I know the conventional wisdom that the pinch adds more wear and tear to a rope, but I've never heard that it amounts to reducing the rope-bearing radius to one biner. In since I first owned d-shaped biners, I've almost always reversed and opposed them, and if I've experienced any decrease in the life of my rope, it's been so slight that I haven't noticed. I think rope-on-rock contact is a far greater concern.

I'm with everybody who thinks arguing over lockers, reversed and opposed or otherwise, vs. reversed and opposed non-lockers is a waste of time.

In the thread that I linked to it was suggested that using two lockers with gates to the same side is safer than the same lockers o-n-o.

Nonsense. The whole point of opposing the gates is so that nothing, anticipated or not, can simultaneously open both gates. Opposed gates has been the standard, as far as I know, for longer than lockers were commonly employed.

As for wear, I'll believe that when someone shows me hard data. And I'd guess that loading has the opposite effect from pinching, aligning the biners so the rope is on the broadest part of both.

Edit: I missed something with the last comment above. I was assuming gates on opposite sides but both biners oriented normally. I can't see any good reason for also "opposing" them, if that is the appropriate term, and it is true that in that case the narrow end of one of the "D's" will be part of the rope-bearing surface, potentially contributing ever so slightly to additional sheath wear.

Until shown real contrary evidence, I'd say the differences are negligible, but lots of lowering through biners does (or at least used to) wear the sheath. I knew guides who constantly top-roped who used beefy rescue pulleys instead of biners to cut down on that wear.

When I was guiding (and that was a long time ago), I almost never (as a matter of philosophy) used top-ropes, but when I did I used three carabiners with the middle gate on the other side from the two outer gates---all biners oriented properly. in the current context, this seems to have something to satisfy everyone.

However what you or I climb on was not the question. In the thread that I linked to it was suggested that using two lockers with gates to the same side is safer than the same lockers o-n-o. Since this is the beginners forum I'd like to have that statement verified or debunked.

You'll need some drop testing as part of the statement verification.

For me, I consider o-n-o equivalent to one locker and in certain cases stronger. Also, I'll put the gates on the same side (but still opposed) if it looks like the other side might preferrentially see some action with the rock.

I know the conventional wisdom that the pinch adds more wear and tear to a rope, but I've never heard that it amounts to reducing the rope-bearing radius to one biner.

Sorry if my posting was unclear. I did not mean that it would reduce the rope bearing radius. I meant that the increased friction from the pinch counteracts the decreased friction from a greater radius.

In reply to:

I with everybody who thinks arguing over lockers, reversed and opposed or otherwise, vs. reversed and opposed non-lockers is a waste of time.

Well you are right. But after all this is the beginners forum and I thought it might be a good idea to crush a myth before it went any further.

If you're using 2 lockers it doesn't matter how you orient them. They're going to flip around sometimes. One of them is going to unscrew sometimes. So what?

Nobody gets hurt top-roping because of the orientation of lockers at the anchor. They get hurt because a n00b belayer drops them, or they fuck up cleaning and rapping, or a rock falls on their head, or they noticed their girlfriend checking out the roided up beefcake on the route next door.

it is suggested that opposite and opposed loockers at a top rope anchor is somehow less safe than double lockers oriented.

Don't misrepresent my statement. I did not say O&O locking biners are always unsafe, just that under certain circumstances they can be problematic: causing gate abrasion on the rock or gate opening by the rock, and causing pinching of the rope with D-shaped biners (with which it is far more sensible to orient the spines on the same side).

And what I also pointed out is that O&O is a vestige of the non-locking oval carabiner days in which this was the only way to create a secure top-rope anchor. A single locking carabiner, properly used, is as safe as two O&O non-lockers, which is why we use a single locker on our harness for belay and rappel, at the belay station and everywhere else that security is required.

The primary reason we still use two 'biners at the top rope anchor is to increase the bend radius of the rope and reduce the internal friction from falling or lowering over a tight radius (bend radius is ideally at least 4x rope diameter).

So, since two 'biners are necessary to reduce rope friction and wear but opposing lockers are not necessary for security and might create problems unless they are free-hanging, a wise rigger would use his/her noggin and orient the carabiners in the most appropriate way for the particular application.

That was all I said on this subject. No new 11th Commandment. No absolute statement about O&O 'biners. No new mythology to get hugepedro's shorts in a twist.

The primary reason we still use two 'biners at the top rope anchor is to increase the bend radius of the rope and reduce the internal friction from falling or lowering over a tight radius (bend radius is ideally at least 4x rope diameter).

However an experienced rescuer, rigger, guide and whatever else you claim to be really should know that adding karabiners increases the friction at the top anchor.

The theoretical reasons for this are well understood and the effect has been known by mountaineers for generations.

The experiment is easy enough, probably you´ll manage it yourself instead of elevating yourself on the shoulders of someone you don´t understand.

At the risk of giving pedro another opportunity to start an endless flame war, I will emphatically disagree with this statement.

Most lockers are screw locks. Screw lock 'biners, if oriented vertically, should always have the gate opening facing downward so that the locking sleeve is less likely to unscrew.

And that's a great mnemonic for teaching nubies: screw it down so you don't screw up.

No need for flames, just show me evidence.

I've not seen any tendency for them to unscrew one way or the other. If there's enough friction against the rock to screw the sleeve it will go up or down. Gravity won't prevent or cause a screwgate sleeve turning. I've seen them unscrew up plenty of times.

They flip. They get flattened against the rocks so the gates aren't facing away. They don't stay in that orientation. I've seen no evidence that orientation of the biners makes any difference in safety.

I orient them the same way you do, not for safety, for convenience. It's just slightly easier to clip the rope into them that way.

However an experienced rescuer, rigger, guide and whatever else you claim to be really should know that adding karabiners increases the friction at the top anchor.

Now comes Jim to take on the flaming role. Must be a tag team. If you would like to present an explanation, rather than merely vent, you might actually contribute to this discussion.

As your own published reports indicate, the smaller the sheave diameter the greater the internal friction (and potential exceeding of elastic fiber limit) and the lower the efficiency (more energy lost to internal friction).

As you well know from the capstan formula, friction around a pole varies exponentially with angle of wrap and friction coefficient and is independent of surface area of contact, other things being equal.

Given that the angle of contact (180° for a slingshot belay) is the same with one or two carabiners, and the friction coefficient is the same in either case, perhaps you'd care to explain how double carabiners at a top-rope change of direction increases friction?

You´ve been reading too many papers by rescuers, if you read all the way to the bottom of what I have written to the bibliography you will find after the link the following:- "Stephen Attaway on friction and deriving Amonton´s capstan formula. Interesting mathematics but flawed." That was a polite hint that it is completely wrong.

And if you (or he for that matter) bothered to do the experimentation or review bending theory or try some test calculation using the theory and match the results to known experience you (and he) would discover that Amontons capstan theory is inapplicable in a circumstance where the bending object has any moment of inertia. He is wrong and you are wrong.

The radius of an object doesn´t change by placing another object beside the first, any child can see that. And the result of adding one part of a radius offset to another is that the rope bends, straightens and bends again so the work of bending has to be done twice increasing the resistance.

Get a spring balance, pull a rope with a weight over a karabiner and then add more karabiners. You will see the truth.

Yes, I know that you don't think much of Attaway's friction formulae. And you also acknowledge the math is far too complicated for even the great Titt to come up with a unified theory of everything.

I'll accept your theory. I measure (with crude instrumentation) a 12% increase in friction going from a single carabiner to two.

But I continue to assert that the reason we use two carabiners in a top rope belay, even when no longer needed for security, is to increase the overall bend radius (effective sheave diameter) and decrease the probability of damaging the rope fibers.

And what I also pointed out is that O&O is a vestige of the non-locking oval carabiner days in which this was the only way to create a secure top-rope anchor. A single locking carabiner, properly used, is as safe as two O&O non-lockers, which is why we use a single locker on our harness for belay and rappel, at the belay station and everywhere else that security is required.

O&O isn't a 'vestige' of anything and two opposite non-locking biners is still a perfectly fine way to set up a TR today unless you have some sort of commercial or large group activity going on.

And a single locker at the anchor of a TR isn't fine in my book and what happens up at anchors is wholly unrelated to the fact a single locker is used for belaying and rappelling. That application happens on your harness and you can check the status of the gate lock at any time.

And, as a comparative risk in climbing, this whole topic utterly pales compared to the lack of craft and attentiveness in belaying.

No, the primary reason we use 2 biners is for strength and redundancy.

I use two because I bought two matching carabiners long ago, and if I only used one I would have to carry around the other and think up an explanation for why I own it.

Also, I am skeptical about the "screw down or you screw up" theory of gravity. I would imagine the weight of the locking ring to be negligible in comparison to the forces that might turn it in either direction.

Edit: I missed something with the last comment above. I was assuming gates on opposite sides but both biners oriented normally. I can't see any good reason for also "opposing" them, if that is the appropriate term, and it is true that in that case the narrow end of one of the "D's" will be part of the rope-bearing surface, potentially contributing ever so slightly to additional sheath wear. .

O&O is kind of a double negative. If you have one gate facing down and to the right . The second gate up and to the left. If 1 biner rotates 180° then both biner gates are pointing in the same direction.

Just Oppose them, gates left and right. That way if 1 spins it will end up with 1 gate up and 1 down.

No, the primary reason we use 2 biners is for strength and redundancy.

I use two because I bought two matching carabiners long ago, and if I only used one I would have to carry around the other and think up an explanation for why I own it.

Also, I am skeptical about the "screw down or you screw up" theory of gravity. I would imagine the weight of the locking ring to be negligible in comparison to the forces that might turn it in either direction.

Obviously you aren't a REAL climber. You use the other biner for your key ring, duh!

I've had lockers hanging in my gear room for years and gravity has yet to unscrew. But from now on I'll check them every day and I'll be sure to let this forum know if I observe any movement in the sleeves.